1. Scope of the Present Invention
The present invention relates to the field of management of quadruped livestock such as pigs based on measured weight. More specifically, the present invention provides an apparatus and system for weighing livestock and provides the possibility for accurate sorting the livestock according to weight.
2. Background of the Prior Art
Livestock producers now feed the livestock in large automated facilities holding literally hundreds or thousands of animals. An important aspect of efficient livestock production is determining the weight of individual animals in a herd. Animals should be shipped for slaughter at their optimal weight. The animal may not grade as well as possible and feed wasting occurs if an animal is fed too long. If fed for too short a time, an animal may again not grade as well, and the chance to add valuable weight to the animal relatively cheaply at the end of the process is lost.
These considerations are pertinent in pork production. Pigs gain weight relatively quickly as a percentage of body weight. Weight gains vary substantially from pig to pig. A wrong guess as to weight for an individual pig can be costly when measured as a percentage of the selling price. In fact, estimates suggest that additional profit of at least $20.00 per pig is possible by carefully measuring individual pig weight and basing feed selection and shipping decisions on these weight measurements.
The present invention relates to an apparatus and system that can more accurately and reliably track weight changes in individual members a pig herd. This information allows producers to improve weight gain efficiency through sorting by weight for feed mixture and for selecting and scheduling pigs for shipping to slaughter.
Now, every animal weighing system has a way to control access to the weighing station so that only one animal at a time enters the station. Typically, the system has an inlet gate controlled by the system that closes when an animal has passed through the gate. The gate usually operates pneumatically or hydraulically.
To reduce the chance of more than one pig entering the weighing system at a time, the system must accurately sense when a single animal has passed through the gate, and only then close the gate. The gate should not close on the animal because that may agitate or annoy the animal, deterring the pig from again passing through the weighing system and affecting weight gain. Those familiar with livestock such as pigs know that unpleasant experiences with a particular area of the confinement space will train the livestock to avoid the area, resulting in fewer weighing events for the affected livestock.
Some current systems rely on a sensor such as an animal proximity sensor that initiate the closure of the inlet gate upon sensing an animal passing through the inlet gate. Others use an operator-programmed trigger weight on the weighing platform for this purpose.
Both of these systems have inherent problems. Either type of sensing element requires frequent adjustment during the growth of the animals in the herd to reliably sense presence of a single animal. Each may fail to work properly when there is a large variation in sizes or weights of pigs in the herd.
A further problem is simply that of reliability. Livestock pens are inherently dirty places with dust and corrosive manure and urine throughout. Livestock feeders now frequently wash the sites such as watering, feeding, and weighing stations where animals tend to congregate. The water spray during washing can easily damage sensitive electronic components of all kinds. Separate components for sensing animal presence in the weighing station simply provides one more potential failure point.
For accurate weight measurement, systems now typically use two weighing elements supporting the weighing platform as shown in FIGS. 2–4. One weighing element is at the inlet or entry point for inlet and another at the exit. Load cell 35 in FIG. 2 senses inlet point weight and load cell 36 senses exit point weight.
Current systems sum the two values provided by the load cells as the animal enters the weighing platform. The average for the sum a number of samples accurately indicates animal weight.